Fig. 4.
Co-expression of Panx1 with CaV1.2(Δ33) alters sensitivity to clevidipine. A). Clevidipine does not affect membrane currents in oocytes expressing Panx1 channels alone, while the Panx1 blocker carbenoxolone (CBX) attenuates the currents. B). Membrane currents induced by voltage ramps from − 100 mV to + 100 mV in oocytes expressing Panx1 alone (blue traces) and in oocytes co-expressing Panx1 and CaV1.2 (magenta). The exclusively voltage activated Panx1 channel is chloride selective, yielding a strong outward current at positive potentials. The net current in the co = expressing cells is considerably smaller, likely because of the non-selective properties of the Panx1 channels under these experimental conditions. A slight left shift of the reversal potential in the co-expressing cells is consistent with a change in permeability properties. C). Membrane currents induced by voltage steps from − 60 mV to + 60 mV at 0.1 Hz in oocytes expressing CaV1.2 Δ33 alone (top traces) or oocytes co-expressing CaV1.2 Δ33 with Panx1. Records of identical oocytes are shown, where increasing concentrations of clevidipine were applied with 30 minute intervals to allow recovery of the CaV1.2 channels from inactivation. D). Dose-response curves for clevidipine attenuation of currents in oocytes expressing CaV1.2 Δ33 alone (black squares) or oocytes coexpressing Panx1 with CaV1.2 Δ33 (red circles). The co-expressing oocytes were also exposed to Nicardipine (blue triangles).